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254nm紫外光辐照下,溶解性Fe3+的存在有效促进了全氟辛酸(PFOA)的光化学降解.Fe3+浓度为30μmol·L-1时,Fe2(SO4)3,FeCl3和Fe(NO3)3三种溶解性铁盐对PFOA的降解和脱氟没有显著的差别.过量的SO24-与Fe3+具有较强的形成配合物的能力,由软件Visual MINTEQ2.52计算得出,Fe3+与过量的SO42-形成Fe(SO4)+和Fe(SO4)-2两种形态的配合物,其分配比的总和占16.32%,从而减少了PFOA与铁离子形成配合物的机会,进而抑制了其有效的光化学降解;过量的Cl-与Fe3+形成一配位的FeCl2+,其生成量仅占所有铁物种形态总和的0.12%,对PFOA的降解没有明显的影响,理论计算与实验结果相一致.羟基自由基捕获剂-异丙醇的加入未抑制PFOA的降解,二氧化钛的存在亦未促进其降解,进一步表明Fe3+诱导PFOA的光化学降解不是羟基自由基直接作用的结果.
The photodegradation of perfluorooctanoic acid (PFOA) was effectively promoted by the presence of Fe3 + in the presence of 254 nm UV light.The three solubilities of Fe2 (SO4) 3, FeCl3 and Fe (NO3) 3 were detected at the concentration of 30μmol·L-1 Fe3 + Iron salts have no significant difference in the degradation and defluorination of PFOA.The excess ability of SO24- and Fe3 + to form complexes is calculated by software Visual MINTEQ2.52, Fe3 + and excess SO42- form Fe (SO4 ) + And Fe (SO4) -2, the ratio of PFOA to iron ion is 16.32%, which reduces the chances of complex formation of PFOA with iron ion and thus inhibits its effective photochemical degradation. Excess Cl - Formation of a coordination FeFe2 + with Fe3 +, the formation of which only accounts for 0.12% of the sum of the morphologies of all iron species, and has no obvious effect on the degradation of PFOA. The theoretical calculation is consistent with the experimental results. Hydroxyl free radical scavenger - isopropanol Did not inhibit the degradation of PFOA, the presence of titanium dioxide did not promote its degradation, further indicating that the photochemical degradation of Fe3 + -induced PFOA is not the direct result of hydroxyl radicals.